Endothelial Krüppel-like factor 4 modulates pulmonary arterial hypertension

Am J Respir Cell Mol Biol. 2014 Mar;50(3):647-53. doi: 10.1165/rcmb.2013-0135OC.

Abstract

Krüppel-like factor 4 (KLF4) is a transcription factor expressed in the vascular endothelium, where it promotes anti-inflammatory and anticoagulant states, and increases endothelial nitric oxide synthase expression. We examined the role of endothelial KLF4 in pulmonary arterial (PA) hypertension (PAH). Mice with endothelial KLF4 knockdown were exposed to hypoxia for 3 weeks, followed by measurement of right ventricular and PA pressures, pulmonary vascular muscularization, and right ventricular hypertrophy. The effect of KLF4 on target gene expression was assessed in lungs from these mice, verified in vitro by small interfering RNA (siRNA) knockdown of KLF4, and further studied at the promoter level with cotransfection experiments. KLF4 expression was measured in lung tissue from patients with PAH and normal control subjects. We found that, after hypoxia, right ventricular and PA pressures were significantly higher in KLF4 knockdown animals than controls. Knockdown animals also had more severe pulmonary vascular muscularization and right ventricular hypertrophy. KLF4 knockdown resulted in increased pulmonary expression of endothelin-1 and decreased expression of endothelial nitric oxide synthase, endothelin receptor subtype B, and prostacyclin synthase. Concordant findings were observed in vitro, both with siRNA knockdown of KLF4 and promoter activity assays. Finally, KLF4 expression was reduced in lungs from patients with PAH. In conclusion, endothelial KLF4 regulates the transcription of genes involved in key pathways implicated in PAH, and its loss exacerbates pulmonary hypertension in response to chronic hypoxia in mice. These results introduce a novel transcriptional modulator of PAH, with the potential of becoming a new therapeutic target.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arterial Pressure*
  • Case-Control Studies
  • Cells, Cultured
  • Cytochrome P-450 Enzyme System / metabolism
  • Disease Models, Animal
  • Endothelial Cells / metabolism*
  • Endothelin-1 / metabolism
  • Familial Primary Pulmonary Hypertension
  • Human Umbilical Vein Endothelial Cells / metabolism
  • Humans
  • Hypertension, Pulmonary / etiology
  • Hypertension, Pulmonary / genetics
  • Hypertension, Pulmonary / metabolism*
  • Hypertension, Pulmonary / pathology
  • Hypertension, Pulmonary / physiopathology
  • Hypertension, Pulmonary / prevention & control
  • Hypertrophy, Right Ventricular / etiology
  • Hypertrophy, Right Ventricular / metabolism
  • Hypertrophy, Right Ventricular / physiopathology
  • Hypoxia / complications
  • Intramolecular Oxidoreductases / metabolism
  • Kruppel-Like Transcription Factors / deficiency
  • Kruppel-Like Transcription Factors / genetics
  • Kruppel-Like Transcription Factors / metabolism*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Nitric Oxide Synthase Type III / metabolism
  • Pulmonary Artery / metabolism*
  • Pulmonary Artery / pathology
  • Pulmonary Artery / physiopathology
  • RNA Interference
  • Receptor, Endothelin B / metabolism
  • Time Factors
  • Transfection
  • Ventricular Function, Right
  • Ventricular Pressure

Substances

  • Endothelin-1
  • GKLF protein
  • Kruppel-Like Transcription Factors
  • Receptor, Endothelin B
  • Cytochrome P-450 Enzyme System
  • Nitric Oxide Synthase Type III
  • Nos3 protein, mouse
  • Intramolecular Oxidoreductases
  • prostacyclin synthetase